EFFECT OF SUPERIOR VENA-CAVAL HYPERTENSION ON ALLOXAN-INDUCED LUNG INJURY IN DOGS

To investigate how fast and to what extent superior vena caval hypertension (SVCH) increases lung water in acute increased-permeability state, we studied the time course of lung water accumulation for 3 h in anesthetized dogs under different treatments: 1) controls without intervention (5 dogs), 2) SVCH alone (5 dogs), 3) mild lung microvascular injury induced by low-dose alloxan (75 mg/kg) alone (5 dogs), and 4) SVCH coupled with low-dose alloxan (5 dogs). Neither low-dose alloxan alone nor SVCH alone [superior vena caval pressure (Psvc) = 11.0 ± 3.1 (SD) mmHg] increased lung water significantly. The SVCH coupled with low-dose alloxan (Psvc = 11.3 ± 2.7 mmHg) doubled extravascular lung thermal volume measured by the thermal-dye dilution technique within 1 h (5.3 ± 0.9 ml/kg at base line and 10.9 ± 4.7 ml/kg at 1 h), then remained unchanged (12.5 ± 5.7 ml/kg at 3 h). This increase in lung water was confirmed by gravimetric method (5.69 ± 1.71 g/g blood-free dry wt). We conclude that SVCH is one of the factors that may promote lung water accumulation in increased-permeability state.